His favorite cigarettes are from "Black Angel" which may be a reference to the real cigarettes "Black Devil".
He has a fan club.
Zen's phone number is +82)10-9211-%#XZ
According to the RFA Orientation Guidebook:
His email is firstname.lastname@example.org
His special talents include playing the piano, dancing and singing.
His most used app is the camera.
He likes ice cold beer fresh from the fridge and lamb kebab, and dislikes strange food such as snails and foie gras.
He desires a girlfriend or a chance to act on a bigger stage.
His favourite quote is: "You don't see love with your eyes, you see it with your heart."
He has been in a love triangle both with two girls that were best friends. In the end, he turned them both down.
His ideal type are go-getters.
For a first date, he would like to go to a theater show and surprise his date with a bouquet of flowers.
With women, he often looks at their hands to determine the type of job they do.
V considers Zen to be one of his muses and is frustrated that Zen looks even more handsome in photos than he does in real life.
Zen has psychic dreams which often come true.
Zen breaks the fourth wall twice:
When in a conversation with the MC he mentioned about having a weird dream in which they all were just computers, programmed to say certain things. 
In Jumin's route, day 8, the chat Jumin's Change (17:22/5:22 P.M.), if you and Seven tease him about the stuff he watches, he says "Whichever genre it is, it doesn't suit this game's rating."
He heals at an incredibly fast rate. It is noted by the RFA members that he has never caught a cold. 
He debuted as a musical actor at a small theater company when he was 15 (16 by Korean Age) and gained some publicity through the musical 'Tei's Tea Leaf' when he was 18 (19 by Korean Age). 
It has been 5 years since he last had a girlfriend. 
Zen's love of motorcycles may be a slight reference from a popular 1974 book titled "Zen and the Art of Motorcycle Maintenance".
In a phone call, Zen reveals that he was unknowingly the cover model for the French magazine, "Vague." In the same call, he states a game company is creating an elf character based himself and uses his name. 
Vague is a parody of Vogue.
Zen's Route has 29 visual novels in total from Day 5-11 (excluding the party visual novel), some being interactive and others being non-interactive.
He has the most visual novels out of the Casual Story characters.
Zen has the most visual novels on Day 7 (9 in total).
Zen is the only Casual Story character to have interactive visual novels.
In April Fool's DLC, his login ID and password of the messenger are 'ZEN' and '1111' respectively. 
Jumin once gave Zen a hairball of Elizabeth the 3rd as a gift.
Zen's lives at B1 431 Mysterious Tabcco St. in Jingerbread City, SEL 04047.
In Another Story, Zen is illiterate when it comes to modern electronic devices, and aside from his phone, he had outdated devices like the Walkingman and an old 386 computer running on Hindows98; both purchased at junk shops. Seven had to teach him how to use his smartphone and give him a laptop running on Hindows 7.